The most important issue Obama should discuss in China

The end of July marked the fifteenth consecutive month of record-shattering heat worldwide - just the latest evidence of the warming planet.

So far this year, New York City has experienced 11 "bad air" days; the fact that air pollution is getting worse is another example of the extreme conditions scientists say are exacerbated by rising temperatures.

Scientists aren't the only ones who are worried. A new poll shows that Americans are more concerned about global warming and its consequences than at any other time in the last six years. Here in New York, Governor Andrew Cuomo has signed an agreement between states, provinces and cities across the world to help halt global warming.

President Barack Obama will address climate change when he meets with leaders in Hangzhou, China this week. Before doing so, he will stop at Midway Atoll, a coral reef in the Pacific Ocean threatened by rising sea levels. Obama's visit highlights the need for urgent climate action from two of the world's largest carbon emitters, the United States and China. With less than five months left in the White House, Obama is racing to cement his legacy as a leader on climate change.

Obama and his administration have gotten plenty of attention - and rightly so - for their efforts to curb carbon pollution from coal-fired power plants, one of the country's largest sources of carbon pollution. The Clean Power Plan, which aims to lower emissions from the country's power plants by 32 percent below 2005 levels by 2030, remains the centerpiece of Obama's Climate Action Plan. The plan has faced legal challenges and is being tied up in court, but once executed it will reduce more heat-trapping pollution than any other U.S. policy to date.

There's another aspect to the president's Climate Action Plan that's gotten a bit less attention, but is also critically important - and particularly relevant to China. It's his push to clean up diesel trucks, buses, and other heavy-duty vehicles, which account for nearly 50 percent of China's total on-road fuel use.

The U.S. transportation sector recently bypassed coal and gas-fired power plants as the country's largest source of greenhouse gas emissions. While the president had already established new fuel-efficiency standards for cars, pickup trucks and the like, large, commercial trucks and buses remained mostly unregulated. This broad range of larger vehicles - including school buses and eighteen-wheelers - account for only 10 percent of the vehicles on the nation's roads, but contribute a fifth of the pollution. Emissions from these vehicles are expected to surpass that of passenger cars and trucks by the end of the next decade.

Last June, however, the Obama administration proposed regulation to finally clean up heavy-duty vehicles through more stringent greenhouse gas and fuel efficiency standards. The rule, finalized in August, is expected to reduce carbon pollution by 1.1 billion metric tons and oil consumption by up to two billion barrels. It will help the United States meet its 2015 commitment to avoid the most dangerous impacts of global warming, such as extreme weather, drought, and dramatic sea level rise.

The rule will also make freight trucks and other commercial vehicles more fuel-efficient, which will save consumers money as companies, at least in theory, pass along savings on transportation costs. That's in part why several large retailers, including PepsiCo, supported it.

China is in a similar position; carbon emissions from its transportation sector have doubled from 2000 to 2010 and are projected to increase by a further 50 percent by 2020. Heavy-duty vehicles are the primary consumers of fuel, even though they account for only about 10 percent of the country's new vehicle market. They consume 10 to 15 percent more fuel than similar trucks in the United States and other developed markets

• a gap Beijing hopes to reduce as it develops new fuel-efficiency standards for these vehicles.

As Obama continues to solidify his climate legacy, U.S. efforts to address climate change will reduce pollution, lower oil consumption and save money. The president's continued leadership could have a large impact, particularly if China - so desperately in need of its own reforms, and heading in the right direction - decides to follow suit.

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